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PTEN/MMAC1 expression in melanoma resection specimens.
M Deichmann1, M Thome, A Benner
1Department of Dermatology, University Clinics of Heidelberg, Vossstrasse 2, 69115 Heidelberg, Germany. martin_deichmann@med.uni-heidelberg.de
British Journal of Cancer
|November 28, 2002
Summary
PTEN/MMAC1 gene alterations may play a role in melanoma development. While mRNA and protein levels were not significantly reduced, mutations were found, potentially affecting tumor suppressor function.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- PTEN/MMAC1 is a tumor suppressor gene located on chromosome 10q23.3.
- This region is frequently affected by deletions in melanomas.
- PTEN/MMAC1 is a candidate tumor suppressor for melanoma.
Purpose of the Study:
- To investigate the role of PTEN/MMAC1 in melanoma development.
- To analyze PTEN/MMAC1 expression and mutations in melanoma samples.
Main Methods:
- Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) for mRNA expression.
- Immunohistochemistry for protein expression.
- Sequencing of PTEN/MMAC1 cDNAs.
Main Results:
- No statistically significant down-regulation of PTEN/MMAC1 mRNA was observed in melanomas compared to nevi.
- PTEN/MMAC1 protein expression was not lost in melanomas.
- Three point mutations (all silent) and two nucleotide deletions (frameshifts) were detected in melanoma samples.
- The frameshift mutations resulted in the loss of a putative PDZ-targeting consensus sequence.
Conclusions:
- Alterations in PTEN/MMAC1, specifically frameshift mutations affecting the C-terminus, may contribute to melanoma development.
- Loss of the PDZ-targeting motif could impair PTEN/MMAC1 localization and function.
- PTEN/MMAC1 mutations are implicated in a subset of melanomas.